Roger Federer sent the saddest tweet of the Olympics opening ceremony

The Olympics opening ceremony is a cool moment for Olympians to soak in the magnitude of their accomplishments.

If you checked Olympians' social media accounts Friday night, many were uploading pictures and videos of the parade of nations, calling it the coolest moment of their careers.

This is not what Roger Federer was doing Friday night, however. Federer had to withdraw from the Olympics less than two weeks away from the games due to a knee injury. He will miss the rest of the season.

So, on Friday night, Federer was, sadly, watching his home nation of Switzerland at the opening ceremony on TV and tweeted about it.

At 34 years old, this was likely Federer's last Olympics.

Poor Roger. 

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